Toothbrush back and handle unit



FIG. 1 is a side elevational view of a toothbrush back and handle unit showing my new design, the opposite side being a mirror image;

FIG. 2 is a top plan view thereof;

FIG. 3 is a left end elevational view thereof;

FIG. 4 is a right end elevational view thereof; and

FIG. 5 is a bottom plan view thereof. 

The ornamental design for a toothbrush back and handle unit, as shown and described. 